Offset variable angle connection assembly

ABSTRACT

Systems for securely connecting a spinal implant to a bone anchor by using an offset connection assembly. The variable angle connection assembly is able to securely connect the spinal implant to the anchors even when there is a variance in the angle and position of the anchors with respect to the spinal implant. The connection assembly will not inadvertently lock the components of the connection assembly preventing the relative movement of the components.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.14/662,284 filed on Mar. 19, 2015, which is a continuation of U.S.patent application Ser. No. 14/330,023 filed on Jul. 14, 2014, now U.S.Pat. No. 9,011,496, which is a continuation of U.S. patent applicationSer. No. 13/278,471 filed on Oct. 21, 2011, now U.S. Pat. No. 8,808,331,which is a continuation application of U.S. patent application Ser. No.12/686,134 filed on Jan. 12, 2010, now U.S. Pat. No. 8,070,781. Theseapplications are incorporated herein by reference in their entiretiesfor all purposes.

FIELD OF THE INVENTION

The present invention relates generally to a connection assembly, andmore particularly, to a variable angle spinal implant connectionassembly.

BACKGROUND OF THE INVENTION

Spinal deformities, spinal injuries, and other spinal conditions may betreated with the use of spinal implants. Spinal implants are designed tosupport the spine and properly position the components of the spine. Onesuch spinal implant includes an elongated rod and a plurality of boneanchors. The elongated rod is positioned to extend along one of more ofthe components of the spine and the bone anchors are attached to thespinal components at one end and secured to the elongated rod at theother end.

However, due to the anatomical structure of the patient, the spinalcondition being treated, and, in some cases, surgeon preference, thebone anchors may be required to be positioned at various angles anddistances from the elongated rod. As a result, it can be difficult toobtain a secure connection between the elongated rod and the boneanchors.

As such, there exists a need for a connection assembly that is able tosecurely connect an elongated rod to bone anchors despite a variance inthe angle and position of the bone anchors with respect to the rod.

SUMMARY OF THE INVENTION

In a preferred embodiment, the present invention provides a connectionassembly that can be used to securely connect a spinal implant to a boneanchor. In particular, the present invention preferably provides anoffset variable angle connection assembly that is able to securelyconnect the spinal implant to the anchors even when there is a variancein the angle and position of the anchors with respect to the spinalimplant. Additionally, in a preferred embodiment, the present inventionprovides for a medial locking offset bone anchor connection that allowsfor the preservation of adjacent anatomical structure, such as adjacentfacets. Furthermore, in a preferred embodiment, the present inventionprovides a connection assembly that will not inadvertently lock thecomponents of the connection assembly preventing the relative movementof the components.

In a preferred embodiment, the connection assembly comprises a housingmember that has an aperture for receiving a portion of a spinal implant,an opening for receiving a securing member for securing the spinalimplant and a channel for receiving a receiving member. The receivingmember preferably has an aperture for receiving a portion of an anchor,a rim portion having at least one ridge, and a lumen. In addition, in apreferred embodiment, the receiving member is configured and dimensionedto be received in the channel of the housing member so that thereceiving member is rotatably and translatably connected to the housingmember. An interference member is preferably received in the lumen ofthe receiving member and is translatable in the lumen. In a preferredembodiment, an end of the interference member has an anchor contactingsurface for locking the anchor in place.

In a preferred embodiment, the connection assembly further comprises anannular member that is positioned over the receiving member and receivedin the channel of the housing member. Preferably, a face of the annularmember has at least one ridge and the at least one ridge on the rimportion of the receiving member faces the at least one ridge on thesecond face of the annular member. In a preferred embodiment, the ridgesare configured and dimensioned to engage with each other to lockrotational movement of the housing member and the receiving member.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred or exemplary embodiments of the invention, areintended for purposes of illustration only and are not intended to limitthe scope of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a perspective view of one embodiment of a connection assembly;

FIG. 2 is an exploded perspective view of the connection assembly shownin FIG. 1;

FIG. 3 is an elevated side view of the connection assembly shown in FIG.1;

FIG. 4 is a cross-sectional view of the connection assembly shown inFIG. 1 in the direction of arrows A-A; and

FIG. 5 is a cross-sectional view of the connection assembly shown inFIG. 1 in the direction of arrows B-B.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following description of the preferred embodiment(s) is merelyexemplary in nature and is in no way intended to limit the invention,its application, or uses.

With reference to FIGS. 1-4, a preferred embodiment of an offsetconnection assembly 10 is illustrated. The connection assembly 10preferably includes a housing member 12 and an offset receiving member14. The housing member 12 includes an elongated aperture 16 at a firstend for receiving at least a portion of a spinal implant 20, such as aspinal rod, and the offset receiving member 14 includes an aperture 22for receiving at least a portion of an anchor 24, such as a bone screw.The aperture 22 (and anchor 24) is linearly offset from the spinalimplant 20, or in other words, the center of the aperture 22 is offset adistance x from a central axis 8. One of ordinary skill in the art wouldrecognize that although only a bone screw is shown, the aperture 22 ofthe offset receiving member 14 is capable of receiving any number ofanchors including, but not limited to, other orthopedic screws, hooks,bolts, or other similar bone anchoring devices. The housing member 12and the offset receiving member 14 are preferably rotatably connected.The rotatable connection can be of any suitable design, including athreaded connection, a snap-fit, or a captured connection.

In a preferred embodiment, the housing member 12 also includes a secondaperture 26 at the first end for receiving a securing member 28. Thesecond aperture 26 extends from an outer surface of the housing member12 toward the elongated aperture 16. In a preferred embodiment, thesecond aperture 26 is in fluid communication with the elongated aperture16. At least a portion of the second aperture 26 is preferably threadedto receive the securing member 28, but the second aperture 26 can alsobe non-threaded.

The securing member 28 is preferably a threaded set screw, as best seenin FIG. 2, but can be any type of securing member including, but notlimited to, a bolt, a pin, a shoe, an interference member, or a cammember. In a preferred embodiment, the securing member 28 is captured inthe second aperture 26 preventing accidental disengagement of thesecuring member 28 from the housing member 12. The securing member 28 iscaptured in the second aperture 26 by including an overhanging portion29 on the securing member 28 that abuts against the termination of thethreading in the second aperture 26.

With continued reference to FIG. 2, the housing member 12 also includes,in a preferred embodiment, a channel 30 which extends from a second endof the housing member 12 toward the first end of the housing member 12.The channel 30 is in fluid communication with the elongated opening 16.Preferably, at least a portion of the channel 30 includes threading 31interrupted by at least one groove 32 extending from the second end ofhousing 12 toward the first end of housing member 12. In a preferredembodiment, the at least one groove 32 extends towards the first end ofthe housing member only a predetermined amount and preferably includesan end face 33 that defines the end of the groove 32.

The offset receiving member 14, in a preferred embodiment, includes afirst end and a second end, the aperture 22 located between the ends.The offset receiving member further includes a channel 35 and aresilient leg 50. Referring to FIGS. 2 and 5, the offset receivingmember 14, in a preferred embodiment, receives in the channel 35 aconnection member 17 which is generally cylindrical in shape with agenerally cylindrical lumen 15.

The connection member 17 preferably includes threading 63 and a slot 65at one end of the lumen 15, at a first end of the connection member 17.In another preferred embodiment, the lumen 15 may include a taperedshoulder portion 19. The connection member 17 further includes aradially outwardly extending rim portion 34 on a second end that has aplurality of ridges 36 preferably oriented toward the offset receivingmember 14. In a preferred embodiment, the connection member 17 also hasa shoulder portion 38, spaced from the rim portion 34, on the second endof the connection member 17. The connection member 17 is configured anddimensioned to be received within the channel 30 of the housing member12 and be received within channel 35 of the offset receiving member 14.

Turning back to FIGS. 1-5, the offset connection assembly 10 furtherincludes, in a preferred embodiment, an interference member 40, a gear42, a ring member 44, a cap member 45 and an end cap member 46. Theinterference member 40 has a generally cylindrical shape that tapers, inpart, from a second end to a first end. The taper forms a shoulderportion 51. In a preferred embodiment, the first end of the interferencemember 40 has an end portion 48 that is configured and dimensioned toabut a resilient leg 50 on offset receiving member 14. On a second endof the interference member 40, there is a face 49 which preferably isflat, but may also be arcuate and generally conforms to the shape of thespinal implant 20. In another preferred embodiment, the interferencemember 40 has a generally rectangular shape with a first end having anend portion 48 that is configured and dimensioned to abut the resilientleg 50 and a second end that flares outwardly and includes face 49 forabutting the spinal implant. The interference portion 40 is configuredand dimensioned to be received within the lumen 15 of the connectionmember 17.

The gear 42, as best seen in FIG. 2, preferably is generally annular inshape and has a plurality of ridges 52 on one face and at least oneprojection 54 extending radially outwardly from the gear 42. In apreferred embodiment, the gear 42 is configured and dimensioned to fitover the shoulder portion 38 of the connection member 17 and withinchannel 30 of the housing member 12. The gear 42 is preferably orientedso that the ridges 52 face the ridges 36 on the rim portion 34 of theconnection member 17 and the at least one projection 54 is receivedwithin the at least one groove 32 in the housing member 12.

In a preferred embodiment, the ring member 44 is generally annular inshape, has a first face and a second face, and is configured anddimensioned to fit over the connection member 17 and abut against theshoulder portion 38, as best seen in FIGS. 4 and 5. Preferably, the ringmember 44 also is configured and dimensioned to be received within thechannel 30 of the housing member 12. In a preferred embodiment, the ringmember 44 is made from titanium, but the ring member 44 can also be madefrom any biocompatible material including resilient polymers.

The cap member 45, in a preferred embodiment, is generally annular inshape and has a first face and a second face. The cap member 45 includesan extension portion 56 on the first face of the cap member 45 and alumen 60. As best seen in FIGS. 2, 4 and 5, the extension portion 56preferably is threaded along at least a portion thereof and includes aramp portion 57. Although the extension portion 56 preferably includesthreading, in another preferred embodiment, the extension portion maynot be threaded. Preferably, the diameter of the extension portion 56 issmaller than the diameter of the portion of the cap member 45immediately adjacent to the extension portion 56 creating a shoulderportion 58. In a preferred embodiment, the cap member 45 is configuredand dimensioned so the extension portion 56 engages the threading 31 inthe channel 30 of the housing member 12 and the shoulder portion 58abuts the second end of the housing member 12. The lumen 60 of the capmember 45 is configured and dimensioned to receive the connection member17. In a preferred embodiment, the cap member 45 is captured in thechannel 30 of the housing member 12 to prevent the cap member 45 frominadvertently unthreading from the housing member 12.

The end cap member 46, in a preferred embodiment, is generally annularin shape and has a first face and a second face. The end cap member 46includes an extension portion 61 on the first face of the end cap member46. The extension portion 61 preferably is threaded along at least aportion thereof. Although the extension portion 61 preferably includesthreading, in another preferred embodiment, the extension portion maynot be threaded. In a preferred embodiment, the end cap member 46 isconfigured and dimensioned so the extension portion 61 engages thethreading 63 in the lumen 15 of the connection member 17. As best seenin FIGS. 2, 4 and 5, at least a portion of the first face of the end capmember 46 abuts the second end of the offset receiving member 14. In apreferred embodiment, the end cap member 46 is captured in the lumen 15of the connection member 17 to prevent the end cap member 46 frominadvertently unthreading from the connection member 17.

With reference to FIGS. 1 and 3-5, in a preferred arrangement of theelements of the offset connection assembly 10, the housing member 12 isrotatably connected to the offset receiving member 14. As mentionedabove, the connection member 17 is received within the channel 30 of thehousing member 12 and within the channel 35 of the offset receivingmember 14. In a preferred embodiment, a second end of the connectionmember 17 abuts a medial wall 13 located within the housing member 12and a first end of the connection member 17 extends beyond the secondend of the housing member 12. Positioned within the lumen 15 of theconnection member 17 is the interference member 40.

In a preferred embodiment, also received within the channel 30 of thehousing member 12 is the gear 42 which fits over the shoulder portion 38of the connection member 17. The at least one projection 54 on the gear42 is received within the at least one groove 32 and preferably abutsthe end face 33 of the groove 32. The end face 33 of the groove 32 isspaced from the medial wall 13 of the housing member 12 by apredetermined amount, so the gear 42, when placed in the channel 30, isspaced from the rim portion 34 of the offset receiving member 14 by apredetermined amount. Accordingly, the ridges 36 on the rim portion 34are spaced from the ridges 52 on the gear 42. The purpose of thisspacing is important and is explained further below.

In a preferred embodiment, the ring member 44 is also received withinthe channel 30 of the housing member 12 and also fits over theconnection member 17. However, the inner diameter of the ring member 44is smaller than the shoulder portion 38 of the receiving member 14. As aresult, at least a portion of the second face of the ring member 44 willabut the shoulder portion 38. Preferably, the remaining portion of thesecond face of the ring member 44 will contact the gear 42.

The cap member 45, in a preferred embodiment, is also received withinthe channel 30 of the housing member 12 and also fits over theconnection member 17. The threads on the threaded portion 56 engage withthe threads 31 on the channel 30 to threadingly engage the cap member46. Preferably, the threaded portion 56 is threaded into the channel 30until the shoulder portion 58 contacts the second end of the housingmember 12. In this position, the ramp portion 57 of the threaded portion56 abuts the first face of the ring member 44.

The preferred arrangement of the elements, as discussed above, allow thehousing member 12, the gear 42 and the cap member 45 to rotate withrespect to the receiving member 14, the connection member 17, the ringmember 44, the interference member 40, and the end cap member 46. As thehousing member 12 rotates, the gear 42 will also rotate because of theat least one projection 54 located in the at least one groove 32.Likewise, since the cap member 45 is threaded and preferably captured inthe channel 30 of the housing member 12, the cap member 45 also rotateswhen the housing member 12 rotates. In contrast, the connection member17, although captured within the channel 30 of the housing member 12 byvirtue of the cap member 45 and the rim portion 34, is capable ofrotating as well as translating within the channel 30. Similarly, thering member 44, although captured within the channel 30 of the housingmember 12 by virtue of the shoulder portion 38 of the connection member17 and the ramp portion 57 of the cap member 45, is capable of rotatingwithin channel 30. Consequently, the ring member 44 does not rotate whenthe housing member 12 rotates. The receiving member 14 also is capableof rotating with respect to the housing member 12 as the receivingmember 14 is connected to the housing member 12 through the connectionmember 17, which, as just discussed, is capable of rotating with respectto the housing member 12.

A preferred connection of the spinal implant 20 to the anchor 24 throughthe connection assembly 10 is best depicted in FIGS. 1, 2 and 3. In anexemplary use, the anchor 24 is implanted into a component of the spinalcolumn, such as a vertebral body in the spinal column. Preferably, theaperture 22 of the receiving member 14 of the connection assembly 10receives the anchor 24. The aperture 22 is configured and dimensioned toreceive any portion of the anchor 24 allowing the connection assembly 10to be placed anywhere along the length of the anchor 24. Accordingly,the connection assembly 10 can be translated along the anchor 24 untilthe desired position is achieved.

In an exemplary use, the spinal implant 20 is typically placed along atleast a portion of the length of the spinal column in an orientationthat is generally perpendicular to the anchor 24. Preferably, the spinalimplant 20 is also received in the connection assembly 10, where thespinal implant 20 is received in the elongated opening 16 in the housingmember 12. The elongated opening 16 is configured and dimensioned toreceive any portion of the spinal implant 20 allowing the connectionassembly 10 to be place anywhere along the length of the spinal implant20.

Additionally, since the housing member 12 and the receiving member 14are rotatably connected to each other, even if the anchor 24 and thespinal implant 20 are angularly offset, the connection member 10 can beoriented to a desired position to connect the spinal implant 20 and theanchor 24. Furthermore, as mentioned above, the anchor 24 is linearlyoffset from the spinal implant 20, or in other words, the anchor 24 isoffset a distance x from the central axis 8, which is defined asextending from the first end of the housing member 12 to the second faceof the end cap member 46. This linear offset allows for an offsetconnection of the anchor 24 to the spinal implant 20 thereby allowingfor the preservation of adjacent anatomical components, such as theadjacent facets. Once the desired angular orientation and translationalpositioning of the connection assembly 10 with respect to the anchor 24and the spinal implant 20 is achieved, the connection assembly 10 can belocked, securing the anchor 24 and the spinal implant 20.

To lock the connection assembly 10, the securing member 28 is threadedinto the second aperture 26 in the housing member 12 where it contactsand pushes the spinal implant 20 toward the anchor 24. The spinalimplant 20 contacts the face 49 of the interference member 40 and pushesthe interference member 40 towards the anchor 24. As the interferencemember 40 is pushed by the spinal implant 20 towards the anchor 24, theinterference member 40 moves in the lumen 15 of the connection member 17towards the anchor 24, while the connection member 17 remainsstationary. The end portion 48 of the interference member 40 abuts theresilient leg 50, pushing the resilient leg 50 into the anchor 24,which, in turn, pushes the anchor 24 into a sidewall of the aperture 22in the receiving member 14, locking the anchor 24 in place with respectto the connector assembly 10.

As the spinal implant 20 continues to move towards the anchor 24 andcontinues to push the interference member 40, the shoulder portion 51 ofinterference member 40 abuts the walls of the lumen 15 and pushesagainst the walls of the lumen 15 moving the connecting member 17. Asthe connecting member 17 moves, the shoulder portion 38 pushes againstthe second face of the ring member 44. Since the first face of the ringmember 44 abuts the ramp portion 57 of the cap member 46, after apredetermined force is applied to the ring member 44 by the shoulderportion 38, the ring member 44 deflects or bends in the direction of theramp portion 57. With the ring member 44 no longer blocking the shoulderportion 38, the connecting member 17 continues moving towards the anchor24 until the ridges 36 on the rim portion 34 of the receiving member 14engage the ridges 52 on the gear 42. With the ridges 36 and 52 engaged,the relative rotation of the housing member 12 and the receiving member14 of the connection assembly 10 is locked. At this point, the spinalimplant 20 is also locked in place between the threaded member 28 andthe walls of the housing member 12 that define the elongated opening 16.With the spinal implant 20 locked in place, the relative rotation of thehousing member 12 and the receiving member 14 locked, and the anchor 24locked in place, the entire assembly is locked against movement.Adjustments to the entire assembly can be made by loosening the threadedmember 28 and then re-tightening the threaded member 28 once thepreferred positioning and orientation has be achieved.

It is important to note that because of the shoulder portion 38 abuttingthe ring member 44 and the at least one projection 54 of the gear 42abutting the end face 33 of the at least one groove 32, prior to thebending or deflection of the ring member 44, the ridges 36 on the rimportion 34 of the receiving member 14 can not engage the ridges 52 onthe gear 42. This arrangement of elements prevents any inadvertentengagement of the ridges 36, 52 thereby preventing any unintendedrotational locking of the housing member 12 with respect to thereceiving member 14.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

What is claimed is:
 1. A method of securely connecting a spinal implantcomprising: implanting at least one anchor into a vertebral body;positioning a spinal implant along a spinal column; positioning thespinal implant in a housing member of a connection assembly, theconnection assembly comprising: the housing member having a first endand a second end, the housing member having an aperture proximate thefirst end for receiving a portion of the spinal implant and a channelextending from the second end towards the first end, the channel is influid connection with the aperture and oriented generally transverselyto the aperture; a connection member having a first end and a secondend, the connection member having a lumen, the lumen is in fluidcommunication with the aperture of the housing member and orientedgenerally transversely to the aperture of the housing member, the secondend of the connection member is received in the channel of the housingmember so that the connection member is rotatably and translatablyconnected to the housing member; and a receiving member having a firstend and a second end, the receiving member having an aperture forreceiving a portion of the anchor, a resilient leg for contacting theanchor, and a channel extending from the second end to the first end,the channel receives a first end of the connection member; rotating thereceiving member with respect to the housing member to align theaperture with the anchor; connecting the receiving member of theconnection assembly to the anchor.
 2. The method of claim 1, wherein theanchor is linearly offset from the spinal implant.
 3. The method ofclaim 1, wherein the connection assembly has a central axis, and theanchor is offset a distance from the central axis, thereby allowing foran offset connection of the anchor to the spinal implant.
 4. The methodof claim 1 further comprising locking the connection assembly byadvancing a securing member in the housing member.
 5. The method ofclaim 1, wherein the receiving member is rotated relative to the housingmember such that the receiving member is oriented to a desired positionto connect the spinal implant and the anchor.
 6. The method of claim 1,wherein the connection assembly is translated along the anchor until adesired position is achieved.
 7. A method of securely connecting aspinal implant comprising: implanting a first anchor into a firstvertebral body; implanting a second anchor into a second vertebral body;positioning a spinal implant in first and second connection assemblies,each connection assembly comprising: a housing member having a first endand a second end, the housing member having an aperture proximate thefirst end for receiving a portion of the spinal implant and a channelextending from the second end towards the first end, the channel is influid connection with the aperture and oriented generally transverselyto the aperture; and a receiving member having a first end and a secondend, the receiving member having an aperture for receiving a portion ofthe anchor, a resilient leg for contacting the anchor, and a channelextending from the second end to the first end, the channel receives afirst end of the connection member; rotating the receiving member withrespect to the housing member to align the aperture with the anchor;connecting the first connection assembly to the first anchor and thesecond connection assembly to the second anchor.